Objective:

The objective of this research is to measure:
(1) the effects of forest harvesting on nitrogen (N) sinks and interwatershed
transfers of N stored in harvested woody biomass within watersheds covering
a range of areas; and (2) the effects of plot-scale harvests and atmospheric
N deposition on soil C:N ratio recovery across a forest harvest chronosequence.

Approach:

Objective 1 will be tested using the U.S. Department
of Agriculture Forest Service Forest Inventory Analysis (FIA) data and data
on wood harvest export, import, and consumption through time within each of
the 17 major watersheds of New York. Two sinks of N in harvested woody biomass
will be calculated using an ArcGIS-based model. The net change of N in standing
stock (live wood) will be calculated for each watershed as:

Objective 2 will be tested by measuring aboveground and shallow subsurface
C, N, and organic matter pools across a forest harvesting chronosequence. A
harvesting chronosequence will be used to evaluate recovery of soil C:N through
several decades. In addition to C:N ratio recovery, testable variables include
nitrification potential, onsite tree species, soil mass, bulk density, and
soil moisture at each sampling location.

Losses of N in harvested wood should be highest in forested watersheds with
stands averaging 80-120 years. Because of the increased availability of N in
systems with extreme atmospheric N deposition, N assimilation in woody biomass
should be higher in these watersheds. C:N ratio recovery should occur within
one decade as a result of the system’s high N status. Because C:N ratios
typically recover (increase) through time, rates of potential soil nitrification
should decrease (an inverse correlation).

Relevant Websites:

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.